Dilute buffers

On-line sample-stacking techniques " and, more recently, the use of isotacho-phoresis have added to the potential benefits of CE by permitting the concentration of analyte in a large volume by exploiting the difference in the electric field between the dilute sample and system buffer. The electric field is much stronger in the dilute buffer-sample and hence analyte ions move faster until they reach the border with the separation buffer. At this point they slow down, causing the analyte to concentrate as a sharp sample band at the interface. 

Dissolve the protein to be biotinylated at a concentration of at least 1 mg/ml in water or dilute buffer at neutral pH. 

Elute column with 10 MNaCl or dilution buffer. 

The plug flow profile would only be distorted in very narrow bore capillaries with a diameter smaller than the thickness of two double-layers that then overlap. To achieve an undisturbed flow, Knox suggested that the diameter should be 10-40 times larger than 6 [15]. This can easily be achieved in open capillaries. However, once the capillary is packed with a stationary phase, typically small modified silica beads that carry on their own charged functionalities, the distance between adjacent double-layers is only a fraction of the capillary diameter. However, several studies demonstrated that beads with a submicrometer size can be used safely as packings for CEC columns run in dilute buffer solutions [15,35]. 

In columns with thin double layers typical of dilute buffer solution, the electroosmotic flow, ueo, can be expressed by the following relationship based on the von Smoluchowski equation [36] ... 

Each pellet ( dirty microsomal fraction ) was resuspended in 2 mL of ice-cold 1.15 % KCl, collected together and ultracentrifuged again at 100 000 x g for 45 min at 0 °C. The supernatant was discarded and the pellet was rinsed thrice with ice-cold dilution buffer. The rinsed pellet was resuspended in ice-cold 1.15 % KCl to yield a final concentration 20 mg mL of microsomal proteins. The microsomal suspension was immediately aliquoted, frozen and stored at —80 °C. 

A diluted buffer solution (typically more than 10 times) is preferred as sample dilution solvent, but when necessary up to 40% v/v organic solvents can be added. 

Sample dilution buffer 0.067 M sodium citrate, 0.33 mM thymol, pH 2.0, plus the internal standard (see table 1) 0.40 nmol pyridoxine or 2.0-2.4 nmol homoarginine per injection. 

To allow a complete polymerization the separation gel should be made the day before use. To get a smooth surface and to avoid drying the gel, cover the liquid polymerization mixture with a layer of ddH20,1 20 diluted buffer B, or n-butanol. When water or buffer is used, add these liquids at both sides of the sandwich and allow to come together slowly in the middle. After completing the polymerization reaction, a sharp borderUne appears between polyacrylamide gel and liquid. 

After electrophoresis, the gel is fixed and stained as other PAGE gels, too. For semi-dry blotting the 1 20 diluted buffer H is recommended. 

Mix liquid samples in a ratio of 3 vol. of sample to 1 vol. of buffer (fourfold), dissolve solid samples in 1 4 diluted buffer G, heat to 80 °C for 10 min, and add the samples to form a layer below the cathode buffer in the sample pockets of the gel. 

Electrode buffer is 1 5 diluted buffer A, adjusted to pH 8.2 and supplemented with D to a final concentration of 0.5 pg/ml. 

The dilution buffer solutions and SPR running buffer must be the same. The lot of buffer should not be changed during the single experiment. Slight component difference of the buffers affect SPR signals, it is so-called bulk effect. ... 

Hofsten and Lalasidis (15), however, reported that plasteins subjected to gel exclusion chromatography in 50X acetic acid showed no increase in molecular size over that of the reactants. Monti and dost (29) reached the same conclusion based on gel chromatography in DMSO and on analysis of a-amino nitrogen in plasteins. Hofsten and Lalasidis (15) noted that hydrophobic peptides showed unusual elution behavior on sephadex gels in water or dilute buffers, providing a possible explanation for differences in their results compared to those of Arai et al. 

Example A Dilute Buffer Prepared from a Moderately Strong Acid... 

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